Device for occupant protection in a motor vehicle and for anti-theft protection of the motor vehicle

ABSTRACT

The invention relates to a device for occupant protection in a motor vehicle and for anti-theft protection of the motor vehicle, comprising an airbag ( 3 ), which may be inflated with gas by means of a filling device, a transceiver ( 5 ), for electromagnetic waves ( 6 ) and an occupant protection analytical unit ( 81 ) connected thereto. An occupant protection interrogation unit ( 41 ) is arranged on the inflatable airbag ( 3 ), which is wirelessly interrogated by the transceiver ( 5 ). Information on the degree and/or speed of unfolding of the airbag is thus provided to the occupant protection analytical unit ( 81 ). The transceiver ( 5 ) may furthermore wirelessly interrogate a portable anti-theft interrogation unit ( 42 ), for example, a chipcard and hence provide an anti-theft analytical unit ( 82 ) with information about the authorisation of the anti-theft interrogation unit ( 42 ) and/or the separation of the anti-theft interrogation unit ( 42 ) from the transceiver ( 5 ) based on the returned signal.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a device for occupant protection in a motorvehicle and for anti-theft protection of the motor vehicle, with atleast parts of a detection device for detecting the deployment behaviorof an airbag for occupant protection in a motor vehicle also being usedsimultaneously for access control in terms of an anti-theft protectionof the motor vehicle.

In the automobile industry the best possible protection for a vehicleoccupant by means of an airbag that deploys in the event of an accidentis usually ensured when the vehicle occupant to be protected is sittingin an upright position, wearing a seatbelt and leaning back on thevehicle seat, with the result that the occupant maintains a certainminimum distance from the airbag activation unit.

However, in order also to protect such vehicle occupants who are not inthis preferred sitting position as effectively as possible from injuriesin the event of an accident, use is made of devices for occupantprotection in a motor vehicle which adjust the activation behavior of anairbag to take account of such a so-called “out-of-position” sittingposition of a vehicle occupant.

If, for example, a vehicle occupant is in a leaning-forward position, afully deploying airbag can even lead in certain circumstances to aninjury of the vehicle occupant. In this case it is of advantage, forexample, to fire only a first stage of the airbag, in which the airbaginflates only partially and therefore more gently. In certain conditionsit can even protect a vehicle occupant from additional injuries if theinflation of the airbag is totally prevented.

The European patent application EP 0 836 971 A1 discloses a device inwhich the inflation behavior of the airbag is monitored during itsdeployment for the purpose of detecting an “out-of-position” sittingposition of a vehicle occupant:

If an object or a person is located too close to the airbag activationunit, then the airbag cannot deploy unobstructed. The obstructeddeployment of the airbag is detected by the device and indicates an“out-of-position” sitting position of the vehicle occupant. In order toavoid a possible injury to the vehicle occupant due to this identifiedsitting position, the inflation behavior of the airbag is adjustedaccordingly, by the airbag being inflated at a reduced speed forexample.

An infrared transceiver unit is used in order to detect the deviatinginflation behavior of the airbag, which transceiver unit first transmitsinfrared radiation into the airbag and receives back the infraredradiation from the advantageously reflection-coated inner material ofthe airbag. The reflected radiation is evaluated with respect to itstransit time since the transmission and/or with respect to its frequencyshift in different deployment directions of the airbag. This informationon the deployment behavior of the airbag is transmitted to a controldevice which can influence the inflation characteristic of the airbagaccordingly (column 7, line 51, to column 8, line 23, and claim 1 inthat publication).

From a completely different field, the field of anti-theft protection ofa motor vehicle, systems are known which are able to check, bycontactless means, the authorization of a person to gain access to themotor vehicle and only allow authorized persons to access and operatethe motor vehicle.

Worthy of mention in this context is, for example, the anti-theftprotection system disclosed in the unexamined German application 199 57536 A1, which discloses a transceiver unit in a motor vehicle, whichtransceiver unit transmits radar signals that are modulated over a broadbandwidth and then waits for echo signals. A code transmitter whichreceives the radar signal sends an additionally modulated and codedsignal back to the transceiver unit. An evaluation unit analyzes all theecho signals received by the transceiver unit firstly for anauthorization of the code transmitter and secondly in order to determinethe distance of the code transmitter from the transceiver unit.

SUMMARY OF THE INVENTION

The object of the present invention is to create a device and a methodfor occupant protection in a motor vehicle, wherein at least parts ofthe device can also be used for anti-theft protection of the motorvehicle.

This object is achieved by means of a device for occupant protection ina motor vehicle and for anti-theft protection of the motor vehicle asclaimed in claim 1, which device has an airbag that can be inflated withgas by means of a filling device, together with a transceiver device forelectromagnetic waves and an occupant protection evaluation deviceconnected thereto. Disposed on the airbag is an occupant protectioninterrogation unit which can be interrogated by contactless means by thetransceiver device. In this way the occupant protection evaluationdevice is provided with information regarding the degree of deploymentand/or the speed of deployment of the airbag. The transceiver device isalso able to interrogate a portable anti-theft protection interrogationunit by contactless means and thereby provide an anti-theft protectionevaluation device with information regarding the authorization of theanti-theft protection interrogation unit and regarding the distance ofthe anti-theft protection interrogation unit from the transceiver deviceon the basis of the signal returned by the anti-theft protectioninterrogation unit.

In this case the transceiver device is usefully disposed within thevehicle instrument panel, preferably in close proximity to the filleropening of the airbag, so that the electromagnetic radiation transmittedor received by the transceiver device can be transmitted unobstructedinto the airbag or received unobstructed from the surface of thedeploying airbag. It is self-evident that in this case the arrangementwithin the vehicle instrument panel must be embodied in such a way thatsimultaneous use of the transceiver unit for access control is stillpossible all the same.

In an advantageous embodiment as many electronic structural units aspossible of the device according to the invention can be used forreceiving and/or transmitting signals from and/or to an occupantprotection interrogation unit and an anti-theft protection interrogationunit. Shared use of the transmit/receive antenna is conceivable, forexample.

In mutually separate occupant protection and anti-theft protectiondevices, a suitable occupant protection evaluation device is typicallyused for occupant protection and a suitable anti-theft protectionevaluation device is typically used for anti-theft protection. In theinterests of the best possible use of electronic structural units bothfor occupant protection and for anti-theft protection in a motor vehicleit is, however, of advantage if the occupant protection evaluationdevice and the anti-theft protection evaluation device are part of acombined evaluation device accommodated within a single housing.

A corresponding combined evaluation device whose operation as anoccupant protection evaluation device or as an anti-theft protectionevaluation device is set simply by different software operating modes isparticularly suitable.

In a suitable embodiment the occupant protection interrogation unitsthat transmit the radiation received by the transceiver unit back to thetransceiver unit are to be embodied as reflectors disposed on the innersurface of the airbag.

If a plurality of such reflectors are used in an airbag, it isfurthermore of advantage to use polarizing reflectors. If polarizingreflectors of this kind are disposed at different points on the innersurface of the airbag, it is possible to distinguish, on the basis ofthe received polarization level of the electromagnetic radiation, fromwhich reflector unit the received radiation originates.

In order to be able to distinguish a larger number of occupantprotection interrogation units from one another, however, it is alsoadvantageous to embody them as transponders. Transponder units of thiskind receive the electromagnetic wave transmitted by the transceiverdevice and use at least a part of its energy as supply energy forpowering a logic circuit which transmits the received electromagneticwave, modified by means of an individual code, back to the transceiverdevice.

In this case the logic circuit can be embodied in the simplest manner asa switch which merely switches a transmit/receive antenna on or off inaccordance with a stored code. Also possible, however, are morecomplicated logic circuits which allow a correspondingly morecomplicated coding. For example, the logic circuit can also be formed bymeans of an oscillator which actively generates a signal which, uponbeing excited by a signal or a wave from the transceiver device, isradiated back as a wave to the transceiver device. In this case eachoccupant protection interrogation unit can radiate on a differentfrequency. It is also possible to use different modulations at the samefrequency. The important thing, in any case, is that the signals of theindividual occupant protection interrogation units can be differentiatedby the transceiver device.

A method according to the invention for protecting occupants of a motorvehicle and for anti-theft protection of the motor vehicle using one ofthe already described embodiments of the device according to theinvention is the subject matter of claim 9.

When a device according to the invention is used, it makes sense toseparate the operation of a motor vehicle into two modes, the normaloperating mode of the motor vehicle, without completed activation of thefiller device for filling the inflatable airbag, and the activationcase, in which an activation of the filler device for filling theinflatable airbag has already been completed or is imminent.

In the normal operating mode of the motor vehicle the transceiver deviceaccording to the invention serves for anti-theft monitoring of the motorvehicle, whereas in the activation case the same transceiver deviceserves exclusively to determine the degree of deployment and/or thespeed of deployment of the airbag.

In order to be able to separate the two operating modes of the combineddevice according to the invention even more effectively it is also ofadvantage that differently coded signals are used in each case for theinterrogation of the anti-theft protection interrogation unit by thetransceiver device and for the interrogation of the degree of deploymentand/or the speed of deployment of the airbag.

It is furthermore particularly advantageous to use the device accordingto the invention also for monitoring the proper functional performanceof the occupant protection interrogation units, for example thetransponders. The transceiver unit typically transmits signals in anycase at regular intervals in order to interrogate the anti-theftprotection interrogation units, from chipcards for vehicle accesscontrol for example, and evaluates the received signals of theanti-theft protection interrogation units with regard to an accessauthorization of the anti-theft protection interrogation units.

During these regular interrogations of the anti-theft protectioninterrogation units by the transceiver unit, suitable test transmitsignals are transmitted simultaneously or at least offset in timethereto from the transceiver unit to the occupant protectioninterrogation units. The response signals transmitted back by theoccupant protection interrogation units, the transponders for example,are evaluated in terms of specific receive signal parameters, by meansof which the evaluation unit can promptly identify a possiblemalfunction.

A detected malfunction of at least one of the occupant protectioninterrogation units can then be taken by the occupant protectionevaluation device as a reason for adapting the “out-of-position”detection in the case of activation of the device according to inventionto the failure of the corresponding occupant protection interrogationunit, through to shutdown of the “out-of-position” detection. Ifappropriate, the possibility that the occupant protection system isfunctioning only inadequately can additionally be indicated to thedriver of the vehicle in question by means of a warning signal in theform of an airbag warning light.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be described below with reference in each case to anexemplary embodiment of the device according to the invention and of themethod according to the invention, in which:

FIG. 1 shows a device according to the invention in a motor vehicle and

FIG. 2 shows a method according to the invention using the deviceaccording to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a schematic cross-sectional representation of a vehiclecabin with a vehicle seat 1 and a person 2 sitting thereon. An inflatedairbag 3 is equipped with a plurality of occupant protectioninterrogation units 41 which can be embodied as simple reflectors or astransponders. A transceiver device 5 which is connected to an occupantprotection evaluation device 81 transmits electromagnetic waves to theoccupant protection interrogation units 41. The latter return suitablycoded waves 7 which are received by the transceiver device 5 andprocessed by the occupant protection evaluation device 81.

But the transceiver device 5 is active even if the airbag is notinflated. The transceiver device 5 transmits at regular intervalstransmit signals 6 which are received by a code card 42. As shownschematically in FIG. 1, the vehicle occupant carries the code card 42with him in his trouser pocket. The code card 42 transmits a modulatedecho signal back to the transceiver unit 5.

The returned modulated echo signal of the code card 42 is received bythe transceiver unit 5. The received signal is forwarded to theanti-theft protection evaluation device 82, which identifies the echosignals with regard to an access authorization of the code card 42 anddetermines the distance between the code card 42 and the transceiverunit 5. In the present case shown in FIG. 1, although the anti-theftprotection evaluation device 82 detects an access authorization of thecode card 42, it can establish on the basis of the information regardingthe very small distance of the code transmitter 42 from the transceiverunit 5 that the vehicle passenger is located in the interior of thevehicle. As a result of this information the anti-theft protectionevaluation device 82 will not initiate any unlocking of the vehicle.

In order to obtain better information regarding the distance and theprecise position of a code card 42 in relation to the transceiver unit5, the signals of the transceiver unit 5 are compared with the signalsof further transceiver units at other points in the motor vehicle, as aresult of which, based on the known evaluation methods in triangulationmeasurements for example, the precise position of a code card 42 can bedetermined.

If the anti-theft protection evaluation device 82 establishes in thisway that, for example, an authorized code card 42 or a person 1 havingan authorized code card 42 is approaching the vehicle, then theanti-theft protection evaluation device 82 initiates an unlocking of thevehicle and allows the vehicle to put into operation.

The reference numeral 80 indicates a combined evaluation device 80 inwhich the occupant protection evaluation device 81 and the anti-theftprotection evaluation device 82 are located in a single device within ahousing. As already explained above, the combined evaluation device 80can separate the two functionalities of an occupant protectionevaluation device 81 and an anti-theft protection evaluation device 82from each other by reason of a different software mode being providedfor each individual functionality.

FIG. 2 shows a method according to the invention wherein the deviceaccording to the invention is used both for occupant protection in amotor vehicle and for anti-theft protection of the motor vehicle:

In a first method step 11 it is determined whether an activationdecision for the inflation of the airbag 3 is present. This iscommunicated to the occupant protection evaluation device 81 within theevaluation device 80 by the central control unit of the occupantprotection system.

If such an activation decision is present, the deployment status anddeployment speed of the airbag are determined in a second and thirdmethod step 12 and 13 with the aid of the transceiver unit 5 and withthe aid of the occupant protection interrogation units 41 disposed onthe inside of the airbag 3. As already described above, this evaluationtakes place in the occupant protection evaluation device 81 on the basisof the signals 6 transmitted by the transceiver unit and the modifiedsignals 7 which are received back, the return times of which differaccording to the distance of the respective occupant protectioninterrogation unit 41 from the transceiver unit 5, and the frequenciesof which are shifted in different degrees toward higher values accordingto the speed of deployment of the airbag 3 as a result of the Dopplereffect.

The information regarding the respective degree of deployment and speedof deployment of the airbag 3, and in particular the importantinformation resulting therefrom as to whether there is an obstacle inthe deployment space of the airbag 3, is subsequently communicated bythe occupant protection evaluation device 81 within the evaluationdevice 80 to the central control unit of the occupant protection system.This is shown as method step 14 in FIG. 2.

The presence of an obstacle in the deployment space of the airbag 3 canthen lead to the inflation of the airbag 3 being modified such that thevehicle occupant is still afforded the best possible protection by theairbag according to the detected “out of position” sitting position ofsaid vehicle occupant. This can be achieved, for example, in that asecond activation stage for full inflation of the airbag is notactivated.

If no activation decision for the inflation of the airbag 3 is present,the device according to the invention is used in the normal operatingmode. The normal operating mode is likewise illustrated with the aid ofFIG. 2:

In the first method step 15 the transceiver device 5 transmits a codedelectromagnetic signal 6.

In method step 16 the code card 42 receives the coded signal 6, modifiesthe signal, using frequency modulation for example, and transmits amodified signal 7 back to the transceiver device 5.

In the following method step 18 the transceiver device 5 receives themodified signal 7 and forwards it to the anti-theft protectionevaluation device 82 within the evaluation device 80.

In method step 19 the access authorization is checked within theanti-theft protection evaluation device 82 by comparisons of thereceived modified signals 7 with stored samples of receive signalshaving access authorization. In addition, the anti-theft protectionevaluation device 82 determines, possibly using corresponding receivesignals of transceiver units 5 at other points of the motor vehicle, thedistance of the chipcard 42 from the transceiver unit 5 and alsoestablishes in particular whether the code card 42 is located inside oroutside the motor vehicle.

If the code card 42 transmits an access-authorized modified signal 7back to the transceiver unit 5, in method step 20 the vehicle isunlocked or remains unlocked if the chipcard 42 is already locatedinside the motor vehicle.

If the code card 42 does not transmit an authorized modified signal 7back to the transceiver unit 5, the vehicle remains locked (method step21). If the vehicle is additionally equipped with an electronicimmobilizer, the latter also remains activated, with the result that thepossessor of a non-authorized code card 42 can neither enter the vehiclenor, following a forced entry into the vehicle for example, bring themotor vehicle into a state in which it can be driven away.

The just described steps of the method according to the invention usinga device according to the invention for occupant protection in a motorvehicle and for anti-theft protection of the motor vehicle can, ofcourse, also be performed in a different sequence. In this case the onlything that is crucial for the use of a device according to the inventionis that at least parts of a transceiver device are used both fordetermining the degree of deployment of an airbag for occupantprotection and for determining its speed of deployment, and also foranti-theft protection of the motor vehicle by means of a contactlessinterrogation of key code cards, for example chipcards, using microwave,radar or ultrasound signals or similar.

1. A device for occupant protection in a motor vehicle and foranti-theft protection of the motor vehicle, the device comprising: anairbag having a filler device for inflating said airbag with gas; atransceiver device for transmitting electromagnetic waves; an occupantprotection evaluation device connected to said transceiver device; atleast one occupant protection interrogation unit disposed on saidairbag, said transceiver device interrogating said occupant protectioninterrogation unit contactlessly resulting in information regarding adegree of deployment and/or a speed of deployment of said airbag beingprovided to said occupant protection evaluation device; an anti-theftprotection evaluation device; and at least one portable anti-theftprotection interrogation unit being interrogated contactlessly by saidtransceiver device resulting in further information regarding anauthorization of said anti-theft protection interrogation unit and/orregarding a distance of said anti-theft protection interrogation unitfrom said transceiver device on a basis of a signal returned by saidanti-theft protection interrogation unit, said further information beingprovided to said anti-theft protection evaluation device.
 2. The deviceaccording to claim 1, wherein said transceiver device is disposed withina vehicle instrument panel.
 3. The device according to claim 1, furthercomprising at least one shared electronic structural unit for areception and/or transmission of signals of said occupant protectioninterrogation unit and of said anti-theft protection interrogation unit.4. The device according to claim 3, wherein said shared electronicstructural unit is an antenna.
 5. The device according to claim 1,wherein said occupant protection evaluation device and said anti-theftprotection evaluation device form a part of a combined evaluation devicehaving and accommodated within a single housing.
 6. The device accordingto claim 5, wherein said occupant protection evaluation device and saidanti-theft protection evaluation device have different softwareoperating modes in said combined evaluation device.
 7. The deviceaccording to claim 1, wherein said occupant protection interrogationunit is a reflector.
 8. The device according to claim 7, wherein saidreflector is polarizing.
 9. The device according to claim 1, whereinsaid occupant protection interrogation unit is a transponder.
 10. Thedevice according to claim 9, wherein said transponder has a logiccircuit which enables a coded wave to be transmitted back to saidtransceiver device.
 11. A method for protecting occupants of a motorvehicle and for anti-theft protection of the motor vehicle, whichcomprises the steps of: in a normal operating mode of the motor vehicle,without completed activation of a filler device for filling aninflatable airbag, performing the steps of: transmitting a coded signalusing a transceiver device; receiving the coded signal in a portableanti-theft protection interrogation unit; transmitting back, via theportable anti-theft protection interrogation unit, a modified codedsignal to the transceiver device; receiving the modified coded signal inthe transceiver device and forwarding the modified coded signal to ananti-theft protection evaluation device; determining in the anti-theftprotection evaluation device, from the modified coded signal,information regarding an authorization of the anti-theft protectioninterrogation unit and/or regarding a distance of the anti-theftprotection interrogation unit from the transceiver device; in anactivation case, upon completed activation of the filler device forfilling the inflatable airbag, performing the steps of: using thetransceiver device for interrogating signals of an occupant protectioninterrogation unit of the inflatable airbag by a contactless methodresulting in further information; and providing an occupant protectionevaluation unit connected to the transceiver unit with the furtherinformation for determining a degree of deployment and/or a speed ofdeployment of the inflatable airbag.
 12. The method according to claim11, which further comprises: using differently coded signals forinterrogation of the anti-theft protection interrogation unit by thetransceiver device than for interrogation of the degree of deploymentand/or the speed of deployment of the inflatable airbag.
 13. The methodaccording to claim 11, which further comprises in the normal operatingmode of the motor vehicle, without completed activation of the fillerdevice for filling the inflatable airbag: performing an interrogation ofthe occupant protection interrogation unit by the transceiver device atregular time intervals and as a result additional information regardinga proper functioning of the occupant interrogation unit is provided forthe occupant protection evaluation device.